Non-destructive inspection of materials using eddy currents are known. Such methods may be used to detect flaws such as cracks in components. Some methods make use of flat spiral-shaped induction coils to detect the presence of residual stresses in a material. However, these methods do not allow for either the direction or magnitude of strain or stress in a component to be resolved.
Improvement in non-contact stress/strain measurement methods is therefore desirable, for these and other reasons.